Method for Making a Bicycle Hub

ABSTRACT

A method of making a rear hub of a bicycle comprises: swaging a straight pipe into an hour-glass-shaped semi product, extruding the semi-product to form a hub flange, punching a plurality of holes in the hub flange of the semi-product, binding an edge of an end of the semi-product, necking down the edge-bound end of the semi-product, trimming the semi-product, and chamfering the holes of the semi-product to form a chamfer structure on an edge of the respective holes.

This is a divisional application of U.S. patent application Ser. No.11/253,946, which claims the benefit of the earlier filing date of Oct.18, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of making a component of abicycle, and more particularly to a method of making the rear hubs of abicycle.

2. Description of the Prior Art

Hub is an important component disposed in the center of a wheel of abicycle, and the hub is generally in the form of a hollow pipe that isformed at either end thereof with a circular hub flange, and in the hubflange are annularly formed a plurality of through holes for insertionof spokes.

U.S. Pat. No. 4,998,344 discloses a method for manufacturing a hub,which comprises the following steps: rotary swaging a work piece to forma semi-product, the work piece is simultaneously struck by three or moredies from the outer peripheral side so that the semi-product is formedsmoothly and homogeneously, and two bearing cup seats are simultaneouslyformed on both ends of the semi-product; and squeezing both ends of thesemi-product by a right mold and a left mold so as to form a hub.However, this method of manufacturing a hub still has the followingshortcomings that need to be improved:

Firstly, the length of the resultant hub usually exceeds the maximumtolerance because of the factors of the molding tolerance and the lengthtolerance of the work piece.

Secondly, during the swaging process, the radial dimension of the huboften deviates from the preset value. If the hole of the hub is toolarge, then the axle cannot be firmly positioned in the hub, and if thehole of the hub is too small, it will be difficult to assemble the axleinto the hub.

The present invention has arisen to mitigate and/or obviate theafore-described disadvantages.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a method ofmaking a rear hub of a bicycle, and the method comprises the steps ofswaging, extruding, punching, edge binding, necking and trimming andchamfering. Through the above steps, the rear hub can be made morecompact and the strength of the rear hub can be strengthened.

A method for making a rear hub of a bicycle in accordance with thepresent invention comprises the following steps:

swaging a straight pipe into an hour-glass-shaped semi product;

extruding the semi-product to, form a hub flange at either end of thesemi-product;

punching a plurality of holes in the hub flange of the semi-product, andthe holes are annularly arranged;

binding an edge of an end of the semi-product;

necking down the edge-bound end of the semi-product,

trimming both ends of the semi-product to a predetermined value; and

chamfering the holes of the semi-product to form a chamfer structure onan edge of the respective holes.

The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawings,which show, for purpose of illustrations only, the preferred embodimentsin accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart in accordance with the present invention ofshowing the steps of making the rear hub of a bicycle;

FIG. 2 is an illustrative view of showing a straight pipe;

FIG. 3 shows that the straight pipe has been swaged into a semi-product;

FIG. 4 shows the semi-product after it is extruded,

FIG. 5 shows the semi-product after it is punched;

FIG. 6 shows the semi-product after it is trimmed;

FIG. 7 shows the semi-product after its edge has been bound;

FIG. 8 shows the semi-product after its end has been necked down; and

FIG. 9 shows the resultant product after being chamfered.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-9, a method of manufacturing a rear hub of abicycle in accordance with the present invention is shown and comprisesthe following steps:

A, swaging: placing a straight pipe 21 (work piece) into a mold andswaging it into an hour-glass-shaped semi product 22, as shown in FIG.10.

B, Extruding: extruding the semi-product 22 to form a hub flange 23 ateither end of the semi-product 22, as shown in FIG. 11.

C, Punching: punching a plurality of holes 24 in the hub flange 23 ofthe semi-product 22, as shown in FIG. 12, wherein the holes 24 areannularly arranged;

D, binding: binding the edge of an end of the semi-product 22 to makethe size of the end of the semi-product 22 satisfy the requirement.

E, necking down the edge-bound end of the semi-product 22 to thepredetermined value, as shown in FIG. 13, for facilitating assembly ofaxial tube, bearing, ball race and etc.

F, Trimming: trimming both ends of the semi-product 22 to thepredetermined value.

G, Chamfering; chamfering the holes 24 of the semi-product 22 to form achamfer structure 25 on the edge of the holes 24, as shown in FIG. 16,for quick and easy assembly of the spokes.

Edge binding process not only can make the size of the edge of the endof the semi-product 22 more compact and precise, but also can improvethe semi-product's strength.

It will be noted that the steps of necking, trimming and chamfering canbe performed in any order according to need, for example: the chamferingprocess can be carried out first, then the necking process and then thetrimming process. Or, trimming process can be made before the neckingand chamfering processes.

While we have shown and described various embodiments in accordance withthe present invention, it should be clear to those skilled in the artthat further embodiments may be made without departing from the scope ofthe present invention.

1. A method for making a rear hub of a bicycle comprising the followingsteps: swaging a straight pipe into an hour-glass-shaped semi product;extruding the semi-product to form a hub flange at either end of thesemi-product; punching a plurality of holes in the hub flange of thesemi-product, and the holes are annularly arranged; binding an edge ofan end of the semi-product; necking down the edge-bound end of thesemi-product; trimming both ends of the semi-product to a predeterminedvalue; and chamfering the holes of the semi-product to form a chamferstructure on an edge of the respective holes.
 2. The method for making arear hub of a bicycle as claimed in claim 1, wherein the chamfering stepis allowed to be carried out before the step of necking down theedge-bound end of the semi-product.
 3. The method for making a rear hubof a bicycle as claimed in claim 1, wherein the trimming step is allowedto be carried out before the step of necking down the edge-bound end ofthe semi-product.
 4. The method for making a rear hub of a bicycle asclaimed in claim 1, wherein the chamfering step is allowed to be carriedout before the trimming step.
 5. The method for making a rear hub of abicycle as claimed in claim 1, wherein the steps of necking, trimming,chamfering and edge-binding are allowed to be carried out in any order.